The present invention relates to mounting assemblies with damping or shock absorbing characteristics for connecting a vibrating element to a rigid support. More particularly, the present invention relates to an elastomeric mounting assembly with hydraulic damping for supporting or mounting a motor vehicle engine on a motor vehicle frame or other member.
Internal combustion engines and other power plants used to propel vehicles produce various forms of vibrations which are undesirably transmitted to the associated vehicle frame or other supporting structure if not properly dampened. Difficulties arise in properly dampening the vibrations, however, as the vibrations may range from high to low amplitude and high to low frequency depending upon the operating conditions of the engine. An engine mount must be hard and provide high damping where operating conditions give engine bounce and soft with low damping for engine isolation.
One engine mount assembly designed to dampen various forms of engine vibrations is disclosed in U.S. Pat. No. 4,489,921 issued Dec. 25, 1984 to Martin. The Martin patent relates to a resilient engine mount having two elastomeric support means with resistance damping characteristics in order to dampen various forms of engine vibrations whether high or low amplitude or high or low frequency. Another type of mount developed to handle different vibrations is the hydraulic engine mount. For example, U.S. Pat. Nos. 4,159,091 issued June 26, 1979 to Salver, et al.; 4,277,056 issued July 7, 1981 to Ticks; 4,383,679 issued May 17, 1983 to Kakimoto and U.K. patent Application No. 2,041,485A published Sept. 10, 1980 to Ticks disclose various fluid-damped elastomeric mountings for damping vibrations of varying characteristics. However, there still remains a need for an improved engine mount which effectively dampens vibrations of varying frequency and amplitude and, in particular, isolates engine vibration from the frame or other supporting structure and also minimizes engine bounce.
Therefore, in accordance with the present invention, an elastomeric engine mount with hydraulic damping is provided. The engine mount resiliently attaches a vibrating body such as an automotive engine to a vehicle frame or other supporting member. The engine mount has a housing which encloses a pair of chambers which are in selective fluid communication with each other through a valve which operates depending upon the vibration encountered. For low amplitude engine vibration, the valve is open and allows fluid to flow between the chambers. The low amplitude vibrations are elastomerically damped with a low damping effect. For high amplitude vibrations, the valve closes to restrict fluid flow between the two chambers. The high amplitude vibrations are hydraulically dampened by the restricted fluid flow which gives a high damping effect.